Surveyor's low end Total Station - what is average new price?

Factual Questions
1

Did I pay above or below average when I bought this low-end Total Station last summer?

I purchased a Sokkia E-Z Station model EZS21. It was new - never used, that is, though it was a touch dusty and might have been manufactured several years ago.

This device is variously billed as a total station or a theodolite, especially a “construction theodolite” or “utility theodolite” (what the manual calls it). I think Sokkia undershot the market with this, and didn’t know where to sell it, so they discontinued it. Angular accuracies of 2" or 5" are more common now. The literature shows construction applications like aligning walls and windows, mostly not outdoor surveying.

Functionally, it actually is a reflectorless total station, though its specifications are low end. It has 20" angular accuracy on both encoders, and has EDM (electronic distance measurement) by a red laser beam that can reach out to around 800 feet in daylight to reflective tape (the typical target). It only reaches around 100 or 150 feet to light-colored walls indoors, in true “reflectorless” mode. Distance accuracy is 3 mm + 10 ppm. There is no compensator for vertical angle (the EZS20 model has one).

It has an LCD display and also outputs measurement text on an RS232 port, but it has no internal memory. It has a tribrach and circular and plate levels. It has an optical plummet. It came in a big plastic suitcase with battery pack (takes four AA cells) and plumb bob, and the seller threw in a tubular compass.

I bought it from a surveying supply company for $2000.

The reason I want to know if I did OK is that I am shopping for some more surveying equipment and want to know if I should go back to this supply company. Though I don’t really know how to judge the price, everything else about dealing with them was fine.

2

sounds like you got a good deal… Low end equipment, for a very low price. What are you planning to use it for?

3

Thanks, chappachula. My hobby is surveying historic ruins, which combines history and the outdoors and instruments and computer work and math and statistics and CAD programs. Pretty much everything on the magic list.

I had a horrible, horrible little “builder’s transit” from Home Depot. This thing had a vernier scale on the azimuth, but the angles went 0 to 90 to 0 to 90 and back to 0. So, half the time I’m reading the vernier scale to the left of 0, and half the time to the right. Plus, it’s much much easier on that instrument to reset the scale than it is to turn the instrument, so when I go back to check the zero I often find it is way off. And the thing was balanced so that if it wasn’t locked horizontal, it would fall forward 30 degrees or so. Just wretched.

So I bought the total station last summer, and it is amazing how accurate it is and how well it works. I wrote a least squares network fitting program and found that surveying along the railroad tracks in lengths a few hundred feet long, I was getting standard deviations less than 10 mm. I did an indoor project under very nice conditions and the eleven reference monuments I mounted to the wall and remeasured about 20 times from 5 base locations had a standard deviation of one point four millimeters (1.4 mm). Incredible. Usually, the 20" digit of the angle displays the same digit on remeasuring. Really nice.

I also use handheld hiking-style GPS receivers but there are all sorts of limitations for them because they’re not surveying type units. I bought a few GPS receivers from DeLorme and a postprocessing program from them, but the receivers fail to operate most times I try to use them. They won’t connect, won’t turn on, lose their settings, the PC crashes - basically everything that can go wrong that doesn’t directly involve GPS per se, does. So I’m trying to get them “fixed” or get refunded. Thus I’m interested in asking my total station supplier what GPS possibilities he has, if his prices are OK.

Thanks!

4

The total station sounds like a decent deal financially, and more importantly, it sounds like it meets your needs. If I can assume that your typical survey work is most often within a smallish area and you are shooting lots of points off one setup, you’ll achieve great results as evidenced by your indoor experiment. At work, we recently bought a Topcon 5 second gun with bells and whistles for about $6.5K, if that gives you an idea of the value.

For buying GPS gear, ISTR that you already have system set up for post processing. if you are talking about a professional grade receiver to replace consumer grade (WAAS accuracy) stuff, I don’t know if that would be worth your money, depending obviously on what you are trying to do with it. Since you mentioned historical ruins, I can imagine that you would be primarily interested in setting up on some sites and shooting the points of where the artifacts were found. But backsighting and traversing in from benchmarks will be a PITA. IME when you collect GPS data and post-process them, they’re not accurate enough to base a local survey grid on. For the type of work that we do, if we need something surveyed, we survey it, so when choosing a field computer, GPS accuracy is not as important to us as the speed with which we can collect data. Your situation may be different.

However, if your work brings you to different sites and you need to share data with the GIS community and people who typically work with shapefiles, you could consider a device that runs ESRI ArcPad, a stripped-down, yet flexible and extensible GIS that is quite good for data collection.

Aside from that, using GPS doesn’t get really useful again from my point of view until you start “rolling your own” control points in real time using survey grade RTK GPS receivers.

5

>For buying GPS gear, ISTR that you already have system set up for post processing. if you are talking about a professional grade receiver to replace consumer grade (WAAS accuracy) stuff, I don’t know if that would be worth your money…

Great memory, Stan! I do have a system set up for post processing - or, rather, I did. But it barely worked. The GPS and calculating and datum transform and math and statistics parts all worked fine. But the stupid data loggers would fail or dump their data or not turn on or freeze my PC so often that I couldn’t use them, even after maybe 50 hours of work and talking with other users. The manufacturer doesn’t seem too interested in supporting them, either. I guess they are more interested in the new market opening up for automobile navigation, but whatever the reason, there is a dedicated little community of would-be postprocessing consumers all trying to help one another get this buggy product to run, and we’re all frustrated and exasperated, and frequently giving up. A very unhappy turn of events for my hobby.

>…professional grade receiver to replace consumer grade (WAAS accuracy) stuff…

The leap I want to make (again, but successfully this time) is to be able to record the right kind of data for postprocessing. There is a separate issue of how accurate the GPS receiver itself is, meaning, how stable its clock and how elaborate its algorithms and how clean its radio receiver. An inaccurate receiver still delivers much more accurate locations through postprocessing than it does in real time, if it can do both. Given a GPS receiver that can record anything at all, being able more specifically to record data for postprocessing is just a firmware issue. The hardware is the same.

So, what I wish some manufacturer was doing is to build a GPS receiver and logger that included a mode for recording postprocessing data, and was aimed at a price point like $200 or $500 or so. I’d like them to make it inherently as accurate as that price will allow, and not spend anything on color displays and road atlases and other popular consumer features that don’t help measure coordinates.

Sadly, I have to wonder if any manufacturer is inclined to even try, because the one company that did, the one whose products I bought, made such a mess of it. They may have demonstrated (incorrectly) that the business idea is a bad one, and they may have attracted many of the likely customers for such receivers and taught them (incorrectly) that products of this type can’t work.

6

The company got a total station used a few years ago for $3500. Don’t remember the model, but it does stake-out, so a bit more features than yours, it seems. So you probably did okay.

7

>…but it does stake-out, so a bit more features than yours, it seems…

Mine does stake-out, too. I just haven’t used it, because I’m only measuring things that are already built, and forgotten even. It has features for shooting around corners and through things - I mean, it helps you lay out lines that aren’t continuous, though I forget what that is called. It reports heights, allows defining Cartesian coordinates, and a bunch of other things. All I have been interested in is the slope distance and the two angles; what I do with those, I do with my own programs.